The present invention relates to Al (aluminum) alloys with increased electrical resistivity, usable for structures.
Al alloys in the prior art have been known as alloys which have a low electrical resistivity, that is, an excellent electrical conductivity, and accordingly they have been used as materials for electric wires or the like. In recent years, however, there has been a demand for an Al alloy which has a high electrical resistivity, for new applications thereof as structural materials in the art of technology of linear motor vehicles, nuclear fusion reactors such as a tokamak, etc., because those structural materials are subject to a ferromagnetic field.
As is known, the use of an Al alloy in a ferromagnetic field will cause an induced current to be produced. The magnitude of this induced current increases in proportion to a specific electric conductivity of the Al alloy material. For example, a fixed columnar electrically conductive member of a sufficient length is subjected to a magnetic field H uniformly in its longitudinal direction along the centerline thereof, with the magnetic field H being amplified at a rate of dH/dt, the density J of a current flow through the conductive member in its circumferential direction is obtained by the following formula: ##EQU1## where,
.mu.: magnetic permeability,
.sigma.: specific electric conductivity, and
r: radius of the columnar conductive member.
In the meantime, the conductive material in which the current is induced due to the external magnetic field, is subject to a relatively large magnetic force in the direction determined according to the Fleming's Left-hand Rule. To reduce this force, therefore, there is required an Al alloy having an electrical resistivity which is as high as possible.